In typical constructions of composite spars or stringers for aircraft, two “c” shaped composite channels are brought together back-to-back to form the central web and top and bottom flanges of the spar. The two channels are each constructed of a plurality of fiber-reinforced polymer plies that have been pre-impregnated with a resin, or pre-preg plies. When the two “c” shaped channels are brought together, the radiuses of the channels where the central web transitions into the flanges forms a small v-shaped gap along the centers of the top and bottom flanges. A composite radius filler, commonly called a “noodle” is typically employed to fill these gaps.
Noodles have been constructed from unidirectional pre-preg tape. Noodles have also been constructed of pre-preg fabric. However constructed, the noodles are positioned in the gaps in the top and bottom flanges of the composite spar and are co-cured with the channels of the spar.
During curing, temperatures typically reach 350 degrees Fahrenheit. The heating of the spar and subsequent cooling to ambient temperature can cause cracking in the noodle. The noodle in the final spar construction can also crack due to mechanical and/or thermal stresses exerted on the spar in use in an aircraft. Cracks in the noodle weaken the entire spar. It is therefore desirable to improve the overall strength of the composite spar by preventing or reducing the propagation of cracks through the noodles employed in constructing the spar.